P(2ap, ap^2), Q(2aq,aq^2) and R(2ar,ar^2) are points on the parabola x^2 = 4ay.
a) Show that the equation of the normal at P is py+x = 2ap + ap^3.
b) Find the coordinates of the point of intersection of the normals at P and Q.
c) If the normals P,Q and R are constant, show that p +q +r=0.
How on earth do you do this??